v2.3.0 — Readable estate layouts

ProcFlow v2.3.0 — Readable estate layouts

Released as the v2.3.0 layout-quality milestone. The ERD page now arranges a
whole estate so relationships are traceable, not just placed.

Highlights

• Auto arrange on first parse. A freshly parsed schema starts in the
  deterministic layered layout. Reset to declaration order is one click
  away, and any drag, restore, or import keeps manual positions.
• Port-anchored orthogonal routing. Edges leave the referenced card at the
  row of the foreign-key column and enter the referencing card at its column
  row. Paths are orthogonal, travel through the card-free gutters between
  layout columns, and use band corridors plus an outer vertical channel for
  edges that span multiple bands. Gutters are clamped under compact spacing so
  a path never enters a neighbor column.
• Card-safe by construction. Structured routing is used whenever the layout
  came from Auto arrange or the declaration-order default; manual layouts fall
  back to the best-effort orthogonal router. Verified zero path/card
  intrusions on the DB2 sample, a 300-table chain, and a sampled 800-table
  chain.
• Stronger crossing reduction. Median sweeps alternate with a monotonic
  adjacent-transpose pass that only accepts swaps which reduce crossings;
  crossing counts use inversion counting and are reported in the Layout status
  line (for example Auto-arranged 12 entities · 0 crossings · LR).
• Direction and spacing. Layout → Direction supports Auto / Left→right /
  Top→bottom; Auto keeps whichever direction fits a 16:9 viewport better.
  Layout → Spacing adds Compact / Normal / Roomy presets that scale all
  gaps deterministically (DB2 sample: 1780×656 compact vs 2114×824 roomy).
• Pinning. A diamond in each card header pins its position; Auto arrange
  keeps pinned cards exactly and shifts unpinned cards deterministically to
  avoid overlaps. Unpin all clears them; Reset clears pins with the
  layout.
• Downstream banding. Isolated tables and views without declared sources
  move to their own downstream band instead of crowding the root column.

Accuracy and limits

• Auto arrange remains a deterministic near-optimal layout, not a
  minimum-crossing guarantee; arbitrary schema graphs can still cross.
• Structured (card-safe) routing applies to left-to-right layouts; top-to-bottom
  layouts use the best-effort orthogonal router.
• Hub fan-outs use staggered gutters that read as a bundle; a single shared
  trunk with branch stubs is still future work.
• Layouts are UI state and do not affect the SQL analysis, Mermaid export, or
  the workspace snapshot.

Verification

The final local verification recorded for this release includes:

• npm run typecheck, npm run build, npm run test:file, and
  npm run metrics passing;
• golden browser assertions on tests/index.html passing (220/220), including
  the v2.3.0 fixtures for orientation, crossings, pinning, spacing presets,
  banding, and a 300-table overlap check (35/35 schema suite);
• 31/31 UI interaction checks and the hostile-input security suite passing;
• ERD smoke checks: DB2 sample 5/5 orthogonal routes with 0 intrusions; a
  300-table chain 300/300 routes with 0 intrusions; a sampled 800-table chain
  200 paths with 0 intrusions; pin held across an LR→TB re-arrange; first-parse
  auto-arrange with 0 crossings reported;
• runtime archive structure and local-file startup smoke passing
  (procflow-v2.3.0.zip).

Upgrade and distribution

The runtime is self-contained. Use npm run package:runtime to produce the
versioned ZIP and verify .release/SHA256SUMS.txt before distributing it.
Layouts, workspaces, and layout files saved by earlier releases remain
readable.